From a6abc4c150df3111841b90c7df708ca9312660d8 Mon Sep 17 00:00:00 2001
From: Stefan Karpinski <stefan@karpinski.org>
Date: Wed, 9 Dec 2020 18:05:41 -0500
Subject: [PATCH] ssh_known_hosts_file: fix bug with empty list (fix #11)

We should return an empty file if there are no known hosts files
as this will cause no hosts to be considered known, which means
we're defaulting secure here.
---
 src/ssh_options.jl | 3 ++-
 test/runtests.jl   | 2 ++
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/ssh_options.jl b/src/ssh_options.jl
index 49eb433..611d8b5 100644
--- a/src/ssh_options.jl
+++ b/src/ssh_options.jl
@@ -138,7 +138,8 @@ function ssh_known_hosts_file()
     for file in files
         ispath(file) && return file
     end
-    return files[1]
+    return !isempty(files) ? files[1] :
+        isfile("/dev/null") ? "/dev/null" : tempname()
 end
 
 ## helper functions
diff --git a/test/runtests.jl b/test/runtests.jl
index 5e85a2b..e14f6fd 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -109,6 +109,8 @@ end
         # empty
         ENV["SSH_KNOWN_HOSTS_FILES"] = ""
         @test ssh_known_hosts_files() == []
+        file = ssh_known_hosts_file()
+        @test !isfile(file) || isempty(read(file))
         # explicit default
         ENV["SSH_KNOWN_HOSTS_FILES"] = path_sep
         default = joinpath(homedir(), ".ssh", "known_hosts")